Years ago this prodigal filmmaker gave up the business and, elevated to the House of Lords, took up two causes close to his heart: education and communications. When Rupert Murdoch announced his bid to take total control of BSkyB, the British satellite-TV giant, Lord Puttnam was among the first to see how menacing this move was to the diversity of media ownership in the U.K.

Lord David Puttnam attends film-making competition for the London 2012 Olympics at the British Academy of Film and Television Arts on March 22, 2010 in London, England. (Ian Gavan / Getty Images)

But in a political climate where prime ministers—of both the Labour and Tory persuasion—walked in fear of the whim of Rupert Murdoch and where so-called regulators moved the goalposts every time Murdoch found them in his path, raising a red flag against Murdoch’s empire was about as popular as proposing the abolition of the monarchy.

Nonetheless, David Puttnam has three qualities that come in handy when waging a campaign against overmighty barons: the ability to marshal an argument with irrefutable facts, to present them with passion—and a lack of fear about the consequences. As we now know in gruesome detail, opposing the Murdoch empire can attract some odious countermeasures.

The entire Murdoch operation in the U.K. is radioactive.

To be sure, it was The Guardian’s disclosures of the Murdoch newspapers’ appalling use of phone hacking that finally got the public’s attention on a scale that made the BSkyB deal politically untenable for Prime Minister David Cameron.

But, as Puttnam wrote in a powerful piece in The Observer last Sunday, what was really at stake in the deal was “the overriding interest of the citizen.”

For the last year, combining forces with other enlightened voices in the House of Lords, Puttnam has argued that if Murdoch got control of both BSkyB, with its enormous reach in entertainment and sports programming, as well as its Sky News channel, and combined those with his control of his newspapers, The Times and The Sunday Times at the top end of the market and, at the bottom, the News of the World and The Sun, he would enjoy a power over British life and culture beyond the dreams of Charles Foster Kane.

As Puttnam often pointed out, the Brits remain largely unaware of the blatant partisanship of Fox News, Murdoch’s contribution to American television journalism.

Given that Murdoch made no bones about how he used his media power to coerce pliant political leaders, you would imagine that Puttnam’s campaign would have persuaded David Cameron’s culture secretary, Jeremy Hunt, to use the powers he had to block the deal. Hunt, however, was resistant to the public-interest argument. In the same way that Cameron compromised himself with the inexplicable hiring of Andy Coulson as his spin doctor, a man mired in the hacking culture of the Murdoch tabloids, Hunt seemed terrified of defying the mighty mogul.

How different it is now. The entire Murdoch operation in the U.K. is radioactive. The spineless ministers and regulators had no choice but to express their shock and horror that such things were possible—and, with today’s all-party consensus that the BSkyB should be dropped, it was.

When the history of Murdoch’s dark hold on British politics and journalism is definitively written, the list of those who consistently stood up to him will be shamefully short. And at the head of it should be Lord Puttnam of Queensgate, a local hero indeed.